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Overview of basic concepts in Statistics and Probability - SAMSI

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Gaussian r<strong>and</strong>om variables<br />

<strong>Overview</strong> <strong>of</strong><br />

<strong>basic</strong> <strong>concepts</strong><br />

<strong>in</strong> <strong>Statistics</strong><br />

<strong>and</strong><br />

<strong>Probability</strong><br />

Avanti<br />

Athreya<br />

Prelim<strong>in</strong>aries<br />

Important<br />

distributions,<br />

scal<strong>in</strong>g laws,<br />

<strong>and</strong> the CLT<br />

Parametric<br />

estimation <strong>and</strong><br />

hypothesis<br />

test<strong>in</strong>g<br />

A cont<strong>in</strong>uous r<strong>and</strong>om variable is called Gaussian or normal with<br />

parameters µ <strong>and</strong> σ if it has a density given by<br />

f (x) = 1<br />

σ √ (x−µ)2<br />

e− 2σ 2<br />

2π<br />

The expected value <strong>of</strong> X is µ, <strong>and</strong> the st<strong>and</strong>ard deviation<br />

√<br />

V (X) is σ.<br />

If X 1 , · · · ,X n are i.i.d N(µ,σ), then any l<strong>in</strong>ear comb<strong>in</strong>ation<br />

∑ n<br />

1 a iX i is also normal!

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